Presentation format influences the strength of causal illusions.

Causal illusions refer to the erroneous perception of causal connections between noncontingent variables. Previous research has demonstrated that the format in which contingency information is displayed can impact causal judgments. On this basis, we examined the effect of graphical displays on the strength of causal illusions and reasoning strategies across three experiments. Study 1 revealed that frequency trees and contingency tables involving icons lead to weaker causal illusions than trial-by-trial presentations or contingency tables with numbers. An assessment of the participants' open responses in Study 2 indicated that stronger causal illusions were associated with reports of less sophisticated reasoning strategies. In Study 3, we directly compared frequency trees and contingency table visualizations. In addition to corroborating previous observations, we found that advanced strategies were more likely when the information was presented in frequency trees. Overall, our findings suggest that the efficacy of frequency trees in reducing causal illusions may be due to their ability to make sophisticated strategies more accessible.